1. Technical Field
The present invention relates to a wheel cover for automotive vehicle, which can be detachably mounted onto a wheel disc of a vehicle road wheel, for protective and/or ornamental purposes.
2. Related Art
As shown in FIGS. 1(a) and 1(b), a road wheel 1 for use with a wheel cover includes a wheel disc 2 secured to an axle of a vehicle, and a wheel rim 3 for mounting a tire thereon. The wheel disc 2 has an axel-mounting hole 4 at its the center portion, bolt holes 5 for securing the road wheel 1 to the axle, which are aligned in the circumferential direction on the radially outer side of the axel-mounting hole 4, and disc openings 6 for dissipating heat, which are aligned in the circumferential direction on the radially outer side of the bolt holes 5. The wheel cover is detachably mounted onto the wheel rim 3, as shown in FIG. 1(c), so as to cover the wheel disc 2 of the road wheel 1 from an outer side.
A typical example of conventional wheel cover as disclosed, for example, in JP 2002-59702 A2 will be described below with reference to FIGS. 2(a) and 2(b). In this instance, the wheel cover 10 includes a wheel cover body 11 made of a rigid synthetic resin, an engagement member 12 integrally projecting from the back surface side of the wheel cover body 11 so as to engage with the wheel rim 3, and a claw-shaped rim-locking portion 13 at the tip end portion of the engagement member 12, which engages with the internal surface of the wheel rim 3. The wheel cover 10 is detachably mounted onto to the road wheel by deflecting the engagement member 12 so that the rim-locking portion 13 of the engagement member 12 is resiliently engaged with the internal surface of the wheel rim 3. On this occasion, the rim-locking portion 13 is biased radially outwards against the inner side of the wheel rim 3 by the resiliency of a ring-shaped retainer 14, so as to stably maintain the wheel cover 10 in place and prevent its withdrawal from the rim 3, for example, under vibrations caused during running, etc.
However, due to the provision of the claw-shaped rim locking portion 13 at the tip end of the engagement member 12 in order to obtain the retaining force for the wheel cover 10 with respect to the road wheel 1, the conventional wheel cover 10 shown in FIG. 2(a) suffers from a problem that is associated with the production technology. More specifically, while such a wheel cover 10 is usually manufactured by injection molding process, the claw-shaped rim locking portion 13 forms an undercut. Thus, as shown in FIG. 2(b), an injection molding die 40 for such a wheel cover 10 cannot be formed only by a stationary die plate 41, and a movable die plate 42 that is movable in the axial direction indicated by arrow x, toward and away from the stationary die plate 41. An additional slide mold member 43 is required for each rim locking portion 13, which must be movable in the radial direction indicated by arrow y, toward and away from the stationary die plate 41, with the result that the injection molding system as a whole becomes large in size and complicated in structure. Also, in order to prevent generation of noise under vibrations, the wheel cover 10 is mounted leaving a gap s between the outer peripheral portion of the wheel cover 10 and the opposite peripheral portion of the road wheel 1. In this instance, by using the slide mold members 43, the gap s is formed at a readily visible position, thereby degrading the appearance of the wheel cover 10. Besides, about six to twelve rim locking portions 13 are generally provided for an ordinary wheel cover, depending upon the diameter of the wheel cover body. The rim locking portions 13 must be large in size and complicated in shape, in order to allow stable engagement of the ring-shaped retainer 14. Therefore, formation of such plurality of rim locking portions 13 not only increases the weight of the wheel cover 10, but also requires the provision of corresponding number of slide mold members 43, i.e., six to twelve slide mold members 43. As a result, the injection mold system as a whole becomes large in size and complicated in structure, thereby increasing the manufacturing cost of the wheel cover.
Another example of conventional wheel cover as disclosed, for example, in JP 2001-225603 A2 will be described below with reference to FIGS. 3(a) and 3(b). In this instance also, the wheel cover 10 includes a wheel cover body 11 made of a rigid synthetic resin, and has vent holes 15 that are arranged close to, and aligned along the outer peripheral portion of the wheel cover body 11. A conical wall 17 projects from an edge portion 16 of the vent hole 15 in the direction substantially perpendicular to the back surface of the wheel body 11. The engagement member 12 extends from a part of the conical wall 17, and a claw-shaped disc-locking portion 18 projects from the tip end portion of the engagement member 12 and folded toward the neighboring vent hole 15, over a bridge portion 19 between the vent holes 15, so as to be engageable with the peripheral portion 7 of the disc opening 6 in the wheel disc 2 of the road wheel 1. This wheel cover 10 is detachably mounted onto the road wheel 1, as follows. The wheel cover body 11 is first of all placed to face the wheel disc 2 of the road wheel 1 so that the vent holes 15 substantially coincide with the disc openings 6 in the wheel disc 2. Then, the engagement member 12 is deflected and the disc-locking portion 18 is inserted into the disc opening 6 in the wheel disc 2 of the road wheel 1. Finally, the engagement member 12 is resiliently engaged with the road wheel 1, with the disc-locking portion 18 in engagement with the peripheral portion 7 of the disc opening 6.
However, in the wheel cover 10 shown in FIGS. 3(a) and 3(b) also, the claw-shaped disc-locking portion 18 projecting from the tip end portion of the engagement member 12 is folded over the bridge portion 19, thereby causing undercut when the wheel cover is manufactured by injection molding. Thus, the slide mold members 43 such as that shown in FIG. 2(b) are still needed, with the result that the injection mold system becomes large in size and complicated in structure. Moreover, the engagement of the wheel cover with the road wheel is achieved solely by the disc-locking portion 18 made of synthetic resin, which may undergo thermal deformation during running of the vehicle, with the result that the wheel cover 10 tends to be readily detached during running.
Furthermore, JP 2000-6602 A2 (or U.S. Pat. No. 6,247,760 B1) discloses a wheel cover having a spoke-shaped wheel disc. In this instance, the engagement member is provided on the back surface of the wheel cover body so as to be engageable with the spoke portion of road wheel. Basically, however, this wheel cover is essentially the same as the wheel cover shown in FIGS. 3(a) and 3(b), both in terms of its mounting structure and associated problems including the requirement for the slide mold members to form the engagement claws. Also, since the wheel cover is engaged with the metallic road wheel by metallic hooks, the surface layer on the road wheel tends to be gradually peeled off during long-term use or by repeated attachment and detachment, thereby causing premature rusting.